Conventionally, in wireless sensor network (WSN) systems, sensor-equipped nodes are interspersed in a given space and work in concert to enable data concerning environmental and physical conditions to be collected. The nodes in such a system transmit and receive the data by multihop communication.
In a related technology, for example, when a given node equipped with a sensor transmits detection related data to another node and the data transmitted by the given node and detection related data of the sensor of the other node do not match, the other node gives notification that an abnormality has occurred. In another related technology, a sensor node calculates a property amount from observed values obtained during a given interval and only when the property amount is determined to have exceeded a given threshold, transmits the observed values obtained during the given interval to a server. Further, in another related technology, only values within a range of physical amounts detected by an integrated state sensor used in a monitoring device are recognized and transmission is performed only when an abnormality is detected. (For examples, refer to Japanese Laid-Open Patent Publication Nos. 2006-285845 and 2010-049584, and International Publication No. 2009/048064.
Nonetheless, with the conventional technologies, when the data obtained by the sensors of the nodes in the system are to be aggregated and collected by a given node, each of the nodes transfers data and the data aggregates at the given node, whereby the volume of communicated data in the system overall increases.